1. Technical Field
The present invention relates to a three-dimensional object recognizing system for discriminating the type of a three-dimensional object by using a distance image constructed by the distribution of three-dimensional distance information.
2. Related Art
In the related art, as the three-dimensional measuring technology based on the image, there is known the image processing by using the so-called stereo method. According to this method, a correlation between a pair of images of the object picked up by the stereoscopic camera comprising two cameras from different positions is found, and then three-dimensional image information (distance image) up to the object are picked up from a parallax caused on the same object based on the principle of triangular survey by using camera parameters such as fitting positions, focal lengths, etc. of the stereoscopic camera. In recent year, the three-dimensional object recognizing system using the image processing of this type is put into practical use. For instance, in the onboard three-dimensional object recognizing system, the technology to recognize the three-dimensional objects on the image such as white line, side wall such as guard rail, curb, or the like extending along the road, vehicle, and the like by applying the grouping process to the data on the distance image and then comparing a distribution of the grouped distance information with previously stored three-dimensional route profile data, side wall data, three-dimensional object data, or the like has been established.
In addition, in order to recognize the three-dimensional object by using the distance image in more detail (to discriminate the type of the three-dimensional object), in JP-A-2001-143072 (which is referred as Patent Literature 1), for example, the body profile discriminating system (three-dimensional object recognizing system) is disclosed. This body profile discriminating system comprises a background cutting-out unit for cutting out only the distance image concerning the object by removing the background from the distance image; a silhouette center/depth mean calculating unit for calculating a silhouette center and a depth mean of the cut object area; an object area translating unit for translating the silhouette center to an image center; a distance image recomposing unit for recomposing newly the distance image by calculating heights of curves, which are defined by the translated distance image, by means of the interpolation when viewed from respective lattice points under the condition that meshes having a predetermined interval are defined on a plane that is parallel with the plane onto which the distance image is projected and is separated by the depth mean; a dictionary database for accumulating the distance images generated via the background cutting-out unit, the silhouette center/depth mean calculating unit, the object area translating unit, and the distance image recomposing unit after the distance images obtained by using an angle of rotation around a surface normal and an angle of the surface normal to an optical axis of a three-dimensional profile measuring system as parameters when respective object models take their stable attitudes on the plane are input; and a collating/discriminating unit for discriminating the object by collating an output from the distance image recomposing unit with information in the dictionary database after the distance image of the object is input.
However, in the technology disclosed in above Patent Literature 1, complicated processes such as translation of the object, recomposition of the distance image, collation between the distance image and the dictionary database, and so on must be taken to discriminate the type of the three-dimensional object.
Also, in the above technology, in order to discriminate the three-dimensional object with good precision, the dictionary database about the object serving as the discrimination object must be formed in detail. However, since much time and labor are required to form such dictionary database, such dictionary database formation is not a realistic measure.
In addition, in some cases the noise, etc. are generated in the picked-up image according to the shooting environment, and the like. In case such the noise, etc. are generated, a mismatching between the pixels, an omission of the distance data, etc. are caused in generating the distance image. As a result, it is likely that a discriminating precision of the three-dimensional object is lowered.